GLSI多层铜布线CMP后BTA去除研究

本文通过静态腐蚀速率的方法分析确立了碱性清洗剂中FA/OⅡ型螯合剂和FA/OⅠ型表面活性剂对BTA的去除规律。通过单因素实验和复合清洗剂的实验优化,确定了去除BTA的清洗剂配方,并通过接触角实验进一步证实实验结果的有效性。最后,将优化后的清洗剂配方在实际生产线上做试验,结果表明能有效去除BTA、CuO晶粒及磨料SiO2,且基本无界面腐蚀。解决了一直难以解决的多层铜布线CMP后有效去除BTA的难题,且该清洗剂成分简单,成本低而且环保。     

碱性多羟多胺螯合剂对Cu CMP后BTA去除作用及机理

苯并三唑(BTA)在微电子领域常被用于铜抛光液中的抗蚀剂,抛光后的BTA残留需要通过化学机械抛光(CMP)后清洗工序从晶圆表面去除,否则会影响器件的性能.通过实验研究了碱性多羟多胺类螯合剂对抛光后晶圆表面残留BTA的去除效果及机理.首先通过傅里叶变换红外光谱(FTIR)和X射线光电子能谱(XPS)研究了BTA在铜表面的吸附状态,发现铜表面的氧化程度会影响BTA在晶圆表面的吸附状态;然后采用体积分数为0.02％、pH值为10.3的碱性多羟多胺螯合剂去除铜表面BTA薄膜.FTIR和XPS测试结果显示,碱性多羟多胺螯合剂可以有效去除铜表面BTA薄膜;最后,通过实验数据研究了碱性多羟多胺螯合剂去除BTA的机理.     

一种对铜抛光后去除苯并三氮唑的新型清洗剂的研究

在化学机械平坦化(CMP)后,铜表面会残留一些颗粒污染(如二氧化硅)和有机物(如苯并三氮唑),这些杂质都会对集成电路造成很大的危害,因此CMP后清洗是必比不可少的过程。尤其是苯并三唑(BTA),它会和铜在其表面生成一层致密的Cu-BTA膜,使铜的表面疏水。这就要求有一种可以有效去除铜表面BTA的清洗剂。本次研究中提出的新型复合清洗剂主要来解决两个问题：一个是BTA的去除问题,另一个是清洗液对铜表面腐蚀的问题。清洗剂的主要成分有两种,一种是FA / OⅡ型碱性螯合剂,它主要用来去除BTA,另一种是FA / O I型表面活性剂,它主要用来解决铜表面的腐蚀问题。通过接触角和电化学的手段来表征BTA的去除情况。表面活性剂的抗腐蚀能力主要通过电化学实验来反映。本文提出的复合清洗剂在不腐蚀铜表面的前提下对于BTA的去除很有优势。关键词： 去除苯并三氮唑;碱性螯合剂;表面活性剂; 腐蚀抑制剂     

新型碱性抛光液各组分对铜化学机械平坦化性能的影响

随着集成电路特征尺寸的减小、晶圆尺寸的增大以及布线层的逐渐增多,加工晶圆过程中实现较高的材料去除速率、较小的片内非一致性(WIWNU)及较小的表面粗糙度已经成为铜化学机械抛光工艺的几大难点.采用正交实验法选取5组抛光液进行Cu CMP实验,系统研究了含有双氧水、脂肪醇聚氧乙烯醚(AEO)、FA/O Ⅰ型螯合剂与苯骈三氮唑(BTA)的碱性抛光液化学组分对铜去除速率、WIWNU的影响,并对铜CMP的各种变化规律做出机理分析.结果表明:采用pH值约为8.6,体积分数为3％的H202,质量分数为0.08％的非离子表面活性剂AEO与体积分数为1.5％的螯合剂的碱性抛光液,在12英寸(1英寸=2.54 cm)铜镀膜片抛光后有助于去除速率达到629.1 nm/min,片内非一致性达到4.7％,粗糙度达到1.88 nm.     

基于化学机械动力学的碱性铜抛光液平坦化机理研究

The planarization mechanism of alkaline copper slurry is studied in the chemical mechanical polishing (CMP) process from the perspective of chemical mechanical kinetics.Different from the international dominant acidic copper slurry,the copper slurry used in this research adopted the way of alkaline technology based on complexation. According to the passivation property of copper in alkaline conditions,the protection of copper film at the concave position on a copper pattern wafer surface can be achieved without the corrosion inhibitors such as benzotriazole(BTA),by which the problems caused by BTA can be avoided.Through the experiments and theories research,the chemical mechanical kinetics theory of copper removal in alkaline CMP conditions was proposed. Based on the chemical mechanical kinetics theory,the planarization mechanism of alkaline copper slurry was established. In alkaline CMP conditions,the complexation reaction between chelating agent and copper ions needs to break through the reaction barrier.The kinetic energy at the concave position should be lower than the complexation reaction barrier,which is the key to achieve planarization.     

柠檬酸在钴基铜互连CMP及后清洗的研究进展

钴(Co)具有较低的电阻率、良好的热稳定性、与铜(Cu)粘附性好等优点,可以替代钽(Ta)成为14 nm以下技术节点集成电路(IC) Cu互连结构的新型阻挡层材料。化学机械抛光(CMP)是唯一可以实现Cu互连局部和全局平坦化的方法,也是决定Co基Cu互连IC可靠性的关键技术。柠檬酸含有羟基,在电离后对金属离子有较强的络合作用,成为Co基Cu互连CMP及后清洗中的主要络合剂。文章评述了柠檬酸在Cu互连CMP及后清洗中的应用和研究进展,包括柠檬酸对Cu/Co去除速率选择比、Co的表面形貌以及Co CMP后清洗中Co表面残留去除等方面的影响,并展望了络合剂及Cu互连阻挡层CMP的发展趋势。     

一种有效解决Cu CMP后残留二氧化硅颗粒的清洗液

摘要：在本文中提出了一种新型有效去除二氧化硅颗粒的FA/O清洗液,其主要成分包括FA/OII型螯合剂和FA/O型活性剂。这种清洗液能够同时去除以物理和化学吸附在晶圆表面的硅溶胶颗粒。 在本文实验过程中通过改变螯合剂和活性剂的浓度, 得出最佳清洗浓度。并且,讨论了这种FA/O碱性清洗剂去除硅溶胶颗粒的机理。根据实验结果可知,FA/OII型螯合剂和活性剂都能够有效去除硅溶胶颗粒。当FA/OII型螯合剂和FA/O活性剂达到最佳配比时,这种新型清洗液能够有效去除硅溶胶颗粒。     

Comparison of novel cleaning solutions with various chelatingagents for post-CMP cleaning on poly-Si film

In this study, various cleaning solutions containing chelating agents with carboxyl acid group (-COOH), such as ethylenediaminetetraacetic acid, citric acid and oxalic acid, were developed for post-poly-Si CMP cleaning. The chelating agent and tetramethylammonium hydroxide (TMAH) were simultaneously added into 2% ammonium hydroxide alkaline solution to promote the removal efficiency on particles and metallic impurities. The effectiveness of various cleaning recipes and their interaction mechanism with the poly-Si surface were studied. We could explain the surface behavior of various cleaning solutions by the different molecular size and charge of chelating agents. Based on the mechanism, the behavior of surface particle and metallic impurity can be realized. The co-existence of TMAH with citric acid or oxalic acid in the alkaline cleaning solutions can significantly enhance the electrical properties of capacitors     

关于FA/O螯合剂降低铜布线片漏电流的研究

简要论述了互连工艺中铜布线取代铝布线的必然趋势,以及铜布线片化学机械抛光(CMP)后进行清洗的必要性。在集成电路制造的过程中,漏电流的危害已经引起了广泛关注。在CMP过程中产生的三种主要表面缺陷对漏电流都有一定的影响,但其中重金属离子对漏电流的影响是最大的。通过使用不同浓度的FA/O螯合剂对铜布线片进行清洗,从而得出最佳的去除金属离子降低漏电流的清洗浓度。为了防止FA/O螯合剂对铜线条造成腐蚀,采用在清洗液中加入缓蚀剂苯并三氮唑(BTA)来有效控制铜线条的表面腐蚀,从而得到理想的清洗结果。25℃时,加入20 mmol/L BTA的体积分数为0.4%的FA/O螯合剂降低漏电流的效果最佳。     

The stability of a novel weakly alkaline slurry of copper interconnection CMP for GLSI

Chemical mechanical polishing (CMP) is one of the important machining procedures of multilayered copper interconnection for GLSI,meanwhile polishing slurry is a critical factor for realizing the high polishing performance such as high planarization efficiency,low surface roughness.The effect of slurry components such as abrasive (colloidal silica),complexing agent (glycine),inhibitor (BTA) and oxidizing agent (H2O2) on the stability of the novel weakly alkaline slurry of copper interconnection CMP for GLSI was investigated in this paper.First,the synergistic and competitive relationship of them in a peroxide-based weakly alkaline slurry during the copper CMP process was studied and the stability mechanism was put forward.Then 1 wt％ colloidal silica,2.5 wt％ glycine,200 ppm BTA,20 mL/L H2O2 had been selected as the appropriate concentration to prepare copper slurry,and using such slurry the copper blanket wafer was polished.From the variations of copper removal rate,root-mean square roughness (Sq) value with the setting time,it indicates that the working-life of the novel weakly alkaline slurry can reach more than 7 days,which satisfies the requirement of microelectronics further development.     

不含抑制剂的碱性抛光液对铜布线平坦化的研究

本文提出一种碱性铜布线抛光液,其不含通用的腐蚀抑制剂,并对其化学机械抛光和平坦化 (CMP)性能进行了研究。首先研究了此抛光液对铜的静态腐蚀速率和抛光速率,并与含抑制 剂的铜抛光液做了对比实验。在静态条件下,此不含抑制剂的碱性铜抛光液对铜基本无腐蚀速率,而在动态抛光过程中对铜有较高的速率。而含抑制剂的抛光液对静态腐蚀速率略有降低,但是却大幅度降低了铜的去除速率。另外,对铜布线的化学机械平坦化研究表明,此不含抑制剂的碱性铜抛光液能够有效的去除铜布线表面的高低差,有较高的平坦化能力。此抛光液能够应用于铜CMP的第一步抛光,能够去除大量多余铜时初步实现平坦化。     

不同压力下螯合剂浓度在碱性Cu CMP中的影响

We propose the action mechanism of Cu chemical mechanical planarization(CMP) in an alkaline solution.Meanwhile,the effect of abrasive mass fraction on the copper removal rate and within wafer non-uniformity(WIWNU) have been researched.In addition,we have also investigated the synergistic effect between the applied pressure and the FA/O chelating agent on the copper removal rate and WIWNU in the CMP process.Based on the experimental results,we chose several concentrations of the FA/O chelating agent,which added in the slurry can obtain a relatively high removal rate and a low WIWNU after polishing,to investigate the planarization performance of the copper slurry under different applied pressure conditions.The results demonstrate that the copper removal rate can reach 6125 °/min when the abrasive concentration is 3 wt.%.From the planarization experimental results,we can see that the residual step height is 562 ° after excessive copper of the wafer surface is eliminated.It denotes that a good polishing result is acquired when the FA/O chelating agent concentration and applied pressure are fixed at 3 vol% and 1 psi,respectively.All the results set forth here are very valuable for the research and development of alkaline slurry.     

碱性抛光液中表面活性剂对铜钽的电偶腐蚀

在阻挡层化学机械抛光(CMP)过程中,阻挡层材料钽(Ta)易与铜(Cu)发生电偶腐蚀.针对这一问题,通过电化学分析方法研究了碱性抛光液中非离子表面活性剂对铜钽腐蚀电位的影响;通过CMP实验研究了非离子表面活性剂对铜钽去除速率的影响.结果表明,随着非离子表面活性剂体积分数增加至9％,铜钽的腐蚀电位均降低.最终确定最佳非离子表面活性剂的体积分数为6％.此时,在静态条件下,铜钽电极之间的电位差为1 mV;在动态条件下,铜钽电极之间的电位差为40 mV,可极大地减弱铜钽电偶腐蚀.同时,铜钽的去除速率分别为47 nm·min-1和39 nm·min-1,铜钽去除速率选择比满足阻挡层CMP要求.     

阻挡层浆料特性对CMP后清洗效力的影响

铜化学机械平面化不同阻挡层浆料的应用引起了铜CMP后清洗的问题。阻挡层浆料的差异包含但不限于pH、研磨剂粒子材料和尺寸及铜腐蚀的抑制剂。为观察阻挡层浆料对清洗工艺的影响进行了清洗实验。阻挡层浆料不同于pH和所有作为铜抑制剂的BTA材料。抑制性BTA溶液的pH值将确定BTA与铜复合物的特性和随后在清洗工艺中去除这种膜的条件。因此,为了研究pH、化学成份以及阻挡层浆料留在铜表面的BTA与铜的复合物去除的化学程序的影响而改变了清洗工艺。从而发现阻挡层浆料的pH值对各种清洗设备的效力均有影响,而且,某些添加剂和两步化学清洗工艺的使用,改进了可变pH值阻挡层浆料的清洗性能。这种工作的结果表明,在最佳结果中,清洗工艺应该致力于阻挡层浆料方面。     

碱性阻挡层CMP后铜布线粗糙度的影响机理分析

The surface roughness seriously affects the performance of devices after barrier CMP. Due to the high surface roughness of copper line, the local resistance of a device will be high when working, then the copper line will overheat prompting the generation of electro-migration and the circuit will lose efficacy. Reducing the surface roughness of the copper line in barrier CMP is still an important research topic. The main factors influencing the surface roughness of copper line in alkaline barrier slurry are analyzed in the paper. Aimed at influencing the law on the surface roughness of copper line, using a new type of alkaline barrier slurry with a different p H of the chelating agent and changing the content of non-ionic surfactant, we then analyze the influencing law both on the surface roughness of copper line, and the influence mechanism. The experimental results show that with a chelating agent with a low p H value in the barrier slurry, the surface roughness of the copper line is 1.03 nm and it is the lowest in all of the barrier slurries, and with the increase of non-ionic surfactant concentration, the surface roughness of copper line is reduced to 0.43 nm, meeting the demand of further development of integrated circuits.     

通过添加表面活性剂和螯合剂改进硅片化学清洗工艺的研究

通过在传统RCA清洗法所用的SC-1液中,添加表面活性剂四甲基氢氧化铵(TMAH)和/或螯合剂乙二胺四乙酸(EDTA),实验比较了不同清洗方法对颗粒粘污、金属粘污的去除效率;并测试了其对硅片表面粗糙度的影响。用MOS电容结构的击穿电场强度Weibull分布,评价了不同清洗方法所得氧化层的质量。结果表明,上述改进能够显著提高对颗粒粘污和金属粘污的去除效果,同时能省去RCA的SC-2清洗步骤,具有节省工时、化学试剂消耗量小的优势。     

300mm铜膜低压CMP速率及一致性

随着铜互连结构中低k介质的应用,要求CMP抛光过程中必须将压力减小到6.89 kPa以下,传统的化学机械抛光已不符合当前的工艺要求,如何兼顾超低压力下抛光速率和速率一致性成为关键问题.对300 mm Blanket铜膜进行了低压化学机械抛光实验,分析研究了碱性抛光液组分及抛光工艺参数对铜膜去除速率及其一致性的影响.通过...     

Novel cleaning solutions for polysilicon film post chemicalmechanical polishing

Novel cleaning solutions were developed for post-CMP process, surfactant tetra methyl ammonium hydroxide (TMAH) and/or chelating agent ethylene diamine tetra acetic acid (EDTA) were added into the diluted ammonium hydroxide (NH₄OH+H₂O) alkaline aqueous solution to enhance removal of metallic and organic contamination. From the experimental result, it is found that the particle and metal removal efficiency and the electrical characteristics are significantly improved for post-CMP cleaning     

基于PSO-SVM模型的Cu CMP抛光液组分优化

在多层Cu布线化学机械抛光(CMP)工艺中,碱性抛光液组分是影响CMP平坦化效果的重要因素。建立了基于PSO-SVM机器学习算法的模型,将化学机械抛光液组分(磨料、氧化剂、活性剂、螯合剂)及pH值作为输入,铜去除速率作为输出,对Cu-CMP实验数据进行训练和预测,获得优化的抛光液配比,并采用Cu-CMP实验进行验证。结果表明,PSO-SVM模型预测效果良好,预测误差在工业生产允许的范围内,有效降低了抛光液研发实验的盲目性,缩短了研发周期,极大降低了实验成本,提高了研发效率。     

多层铜布线表面CMP后颗粒去除研究

针对目前清洗技术存在的问题进行了详细分析,研究了微电子材料表面污染物的来源及其危害,并介绍了表面活性剂在颗粒去除方面的作用。研究了化学机械抛光(CMP)后Cu布线片表面的颗粒吸附状态,分析了铜片表面颗粒的吸附机理。采用非离子表面活性剂润湿擦洗方法,使Cu表面的颗粒处于易清洗的物理吸附状态。利用金相显微镜和原子力显微镜(AFM)在清洗前后进行对比分析,实验采用聚乙烯醇(PVA)刷子分别对铜片和铜布线片进行清洗,发现非离子界面活性剂能够有效去除化学机械抛光后表面吸附的杂质,达到了较好的清洗效果。